Taurine
| Section2 = | Section3 = | Section4 = | Section5 = | Section6 = | Section7 = | Section8 = }} Taurine, or 2-aminoethanesulfonic acid, is an organic acid. It is also a major constituent of bile and can be found in the lower intestine and in small amounts in the tissues of many animals and in humans as well. Taurine is a derivative of the sulfur-containing (sulfhydryl) amino acid, cysteine. Taurine is one of the few known naturally occurring sulfonic acids. Taurine is named after the Latin taurus, which means bull or ox, as it was first isolated from ox bile in 1827 by German scientists Friedrich Tiedemann and Leopold Gmelin. It is often called an amino acid, even in scientific literature, but as it lacks a carboxyl group it is not strictly an amino acid. It does contain a sulfonate group and may be called an amino sulfonic acid. Small polypeptides have been identified which contain taurine but to date no aminoacyl tRNA synthetase has been identified as specifically recognizing taurine and capable of incorporating it onto a tRNA. Biosynthesis The major pathway for mammalian taurine synthesis occurs in the liver via the cysteine sulfinic acid pathway. In this pathway, the sulfhydryl group of cysteine is first oxidized to cysteine sulfinic acid by the enzyme cysteine dioxygenase. Cysteine sulfinic acid, in turn, is decarboxylated by sulfinoalanine decarboxylase to form hypotaurine. It is unclear whether hypotaurine is then spontaneously or enzymatically oxidized to yield taurine. Taurine in the pharmaceutical and lab setting is synthesized through a combination of cysteine, methionine and vitamin E. It is naturally produced in testicles of many mammals. Urban legends surrounding the source of taurine have included bull urine extract and bull semen. While it's true that taurine is found in both sources, it is not the source of taurine in the pharmaceutical or food industry. And while taurine is sometimes extracted from the intestines of cattle, many food industry sources, including the popular energy drink Red Bull,Redbullusa.com make efforts to use synthesized sources that are vegetarian friendly. Physiological roles Taurine is conjugated via its amino terminal group with chenodeoxycholic acid and cholic acid to form the bile salts sodium taurochenodeoxycholate and sodium taurocholate. The low pKa (1.5) of taurine's sulfonic acid group ensures that this moiety is negatively charged in the pH ranges normally found in the intestinal tract and thus improves the surfactant properties of the cholic acid conjugate, which can be found in many energy drinks today. Taurine crosses the blood-brain barrierUrquhart N, Perry TL, Hansen S, Kennedy J. Passage of taurine into adult mammalian brain. Journal of Neurochemistry 1974 May;22(5):871-2.Tsuji A, Tamai I. Sodium- and chloride-dependent transport of taurine at the blood-brain barrier. Advances in Experimental Medicine and Biology 1996;403:385-91.Salimäki J, Scriba G, Piepponen TP, Rautolahti N, Ahtee L. The effects of systemically administered taurine and N-pivaloyltaurine on striatal extracellular dopamine and taurine in freely moving rats. Naunyn-Schmiedeberg's Archives of Pharmacology 2003 Aug;368(2):134-41. and has been implicated in a wide array of physiological phenomena including inhibitory neurotransmission,Olive MF. Interactions between taurine and ethanol in the central nervous system. Amino Acids 2002;23(4):345-57 long-term potentiation in the striatum/hippocampus,Dominy J Jr, Thinschmidt JS, Peris J, Dawson R Jr, Papke RL. Taurine-induced long-lasting potentiation in the rat hippocampus shows a partial dissociation from total hippocampal taurine content and independence from activation of known taurine transporters. Journal of Neurochemistry 2004 Jun;89(5):1195-205. membrane stabilization,Birdsall TC. Therapeutic applications of taurine. Alternative Medicine Review 1998 Apr;3(2):128-36. feedback inhibition of neutrophil/macrophage respiratory bursts, adipose tissue regulation, calcium homeostasis,Foos TM, Wu JY. The role of taurine in the central nervous system and the modulation of intracellular calcium homeostasis. Neurochemical Research 2002 Feb;27(1-2):21-6. recovery from osmotic shock and prevention of epileptic seizures.El Idrissi A, Messing J, Scalia J, Trenkner E. Prevention of epileptic seizures by taurine. Advances in Experimental Medicine and Biology 2003;526:515-25. It also acts as an antioxidant and protects against toxicity of various substances.Green TR, Fellman JH, Eicher AL, Pratt KL. Antioxidant role and subcellular location of hypotaurine and taurine in human neutrophils. Biochimica et biophysica acta 1991 Jan 23;1073(1):91-7.Gürer H, Ozgünes H, Saygin E, Ercal N. Antioxidant effect of taurine against lead-induced oxidative stress. Archives of Environmental Contamination and Toxicology 2001 Nov;41(4):397-402.Das J, Ghosh J, Manna P, Sil PC. Taurine provides antioxidant defense against NaF-induced cytotoxicity in murine hepatocytes. Pathophysiology 2008 Oct;15(3):181-90. Epub 2008 Aug 3. Supplementation with taurine has been shown to prevent oxidative stress induced by exercise.Zhang M, Izumi I, Kagamimori S, Sokejima S, Yamagami T, Liu Z, Qi B. Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men. Amino Acids 2004 Mar;26(2):203-7. Epub 2003 May 9. It is believed that prematurely born infants lack the enzymes needed to convert cystathionine to cysteine and may therefore become deficient in taurine. Thus, taurine is thought to be a dietary essential nutrient in these individuals and has been added to many infant formulas as a measure of prudence, since the early 1980s. However, this practice has never been rigorously studied, and as such it has yet to be proven to be beneficial, or even necessary.Heird W.C. Taurine in neonatal nutrition—revisited. Arch Dis Child Fetal Neonatal. Ed 89. F473-F474 2004 There is also evidence that taurine is beneficial for adult human blood pressure and possibly, the alleviation of other cardiovascular ailments (in humans suffering essential hypertension, taurine supplementation resulted in measurable decreases in blood pressure). Recent studies have also shown that taurine can influence (and possibly reverse) defects in nerve blood flow, motor nerve conduction velocity, and nerve sensory thresholds in experimental diabetic neuropathic rats. Taurine levels were found to be significantly lower in vegans than in a control group on a standard American diet. Plasma taurine was 78% of control values, and urinary taurine 29%.Laidlaw S, Shultz T, Cecchino J, Kopple J (1988) "Plasma and urine taurine levels in vegans." American Journal of Clinical Nutrition, vol. 47, pp. 660-663. In the cell, taurine keeps potassium and magnesium inside the cell while keeping excessive sodium out. In this sense it works like a diuretic. But unlike prescription diuretics, it is not a cellular poison. Because it aids the movement of potassium, sodium, and calcium in and out of the cell, taurine has been used as a supplementation for epileptics as well as for people who have uncontrollable facial twitches.Kirk J and Kirk K. Inhibition of volume-activated I- and taurine efflux from HeLa cells by P-glycoprotein blockers correlates with calmodulin inhibition. J. Biol. Chem, Nov 1994;269:29389–29394. According to animal studies, taurine produces anxiolytic effect and may act as a modulator or anti-anxiety agent in the central nervous system. Zhang CG, Kim SJ. Taurine induces anti-anxiety by activating strychnine-sensitive glycine receptor in vivo. Annals of Nutrition & Metabolism 2007;51(4):379-86. Epub 2007 Aug 29.Chen SW, Kong WX, Zhang YJ, Li YL, Mi XJ, Mu XS. Possible anxiolytic effects of taurine in the mouse elevated plus-maze. Life Sciences 2004 Aug 6;75(12):1503-11. Taurine is necessary for normal skeletal muscle functioning. This was shown by a 2004 study, using mice with a genetic taurine deficiency. They had a nearly complete depletion of skeletal and cardiac muscle taurine levels. These mice had a reduction of more than 80% of exercise capacity compared to control mice. The authors expressed themselves as "surprised" that cardiac function showed as largely normal (given various other studies about effects of taurine on the heart). Taurine is also used in some contact lens solutions. Taurine has also been shown in diabetic rats to decrease weight and decrease blood sugar. According to one study, daily administration of 1.5g taurine had no significant effect on insulin secretion or insulin sensitivity in humans.Effect of taurine treatment on insulin secretion and action, and on serum lipid levels in overweight men with a genetic predisposition for type II diabetes mellitus. C. Brøns, C. Spohr, H. Storgaard, J. Dyerberg, A. Vaag. European Journal of Clinical Nutrition (2004) 58, 1239–1247. However it is possible that an effect may occur at higher dosages. There is evidence that taurine may exert a beneficial effect in preventing diabetes-associated microangiopathy and tubulointerstitial injury in diabetic nephropathy.Wu QD, Wang JH, Fennessy F, Redmond HP, Bouchier-Hayes D. Taurine prevents high-glucose-induced human vascular endothelial cell apoptosis. The American journal of physiology. 1999 Dec;277(6 Pt 1):C1229-38.Verzola D, Bertolotto MB, Villaggio B, Ottonello L, Dallegri F, Frumento G, Berruti V, Gandolfo MT, Garibotto G, Deferran G. Taurine prevents apoptosis induced by high ambient glucose in human tubule renal cells. Journal of investigative medicine: the official publication of the American Federation for Clinical Research. 2002 Nov;50(6):443-51. Taurine acts as a glycation inhibitor. Studies have shown that taurine treated diabetic rats had a decrease in the formation of advanced glycation end products (AGEs) and AGEs content.Effects of taurine on advanced glycosylation end products and expression of TGF-β in renal cortex of, TsingHua, 2005, http://www.shvoong.com/medicine-and-health/1599878-effects-taurine-advanced-glycosylation-end/Huang JS, Chuang LY, Guh JY, Yang YL, Hsu MS. Effect of taurine on advanced glycation end products-induced hypertrophy in renal tubular epithelial cells. Toxicology and Applied Pharmacology 2008 Sep 12. Taurine and cats Taurine is essential for feline health, as cats cannot synthesize the compound. The absence of taurine causes a cat's retina to slowly degenerate, causing eye problems and (eventually) irreversible blindness — a condition known as central retinal degeneration (CRD), as well as hair loss and tooth decay. It was discovered in 1987 that taurine deficiency can also cause feline dilated cardiomyopathy,.Myocardial failure in cats associated with low plasma taurine: a reversible cardiomyopathy Unlike CRD, the condition is reversible with and supplementation. Taurine is now a requirement of the Association of American Feed Control Officials (AAFCO) and any dry or wet food product labeled approved by the AAFCO should have a minimum of 0.1% taurine in dry food and 0.2% in wet food.AAFCO Taurine and bird development Recent research has provided evidence that taurine is essential in early bird development of passerines. Many passerines, regardless of spider availability, seek out many taurine-rich spiders to feed their young particularly in their youngest stages of life. Researchers later compared the behaviors and development of birds fed a taurine-supplemented diet to a control diet and found that juveniles that were fed taurine-rich diets as neonates were much larger risk takers and more adept at spatial learning tasks. Synthesis and production In 1993, approximately 5,000–6,000 t. of taurine was produced; 50% for pet food manufacture, 50% in pharmaceutical applications.Tully, Paul S. Sulfonic Acids. In Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. Published online 2000. Synthetic taurine is obtained from isethionic acid (2-hydroxyethanesulfonic acid), which in turn is obtained from the reaction of ethylene oxide with aqueous sodium bisulfite.Kurt Kosswig. Sulfonic Acids, Aliphatic. in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, 2000. Another approach is the reaction of aziridine with sulfurous acid. This leads directly to taurine. As a functional food Taurine is used as a functional food in many energy drinks and energy productsThis Ain't No Wine Cooler, John Cloud, Time Magazine, July 17, 2008 Despite being present in many energy foods, it has not been proven to be energy-giving. A study of mice hereditarily unable to transport taurine suggests that it is needed for proper maintenance and functioning of skeletal muscles. However, it has been proven effective in removing fatty liver deposits in humans, preventing liver disease, and reducing cirrhosis in rats.M. D. J. Kerai, Catherine J. Waterfield, S. H. Kenyon, D. S. Asker, J. A. Timbrell Taurine: Protective properties against ethanol-induced hepatic steatosis and lipid peroxidation during chronic ethanol consumption in rats Amino Acids Volume 15, Numbers 1-2 / March, 1998 References External links * Taurine benefits, side effects, sources, and deficiency symptoms * The ultimate hangover cure Category:Acids Category:Amines